Heisenberg writes about the enumeration of quantum numbers and in particular the value for k.

Pauli writes about his theoretical investigation of the Zeeman-effect. He makes remarks about the validity of Landé's shema for certain multiplets.

Heisenberg replies to Pauli's letter about quantum numbers. He also writes on Pauli's use of the summation principle for the calculation of Lande's g value and on the difficulties of the doublet-theory.

Pauli talks about his Zeeman-effect model in the light of Back's experimental results.

Pauli summarizes his Zeeman-effect paper (in: Z. Phys. : 16 (1923), pp.155).

Pauli thanks Landé for sending him Back's and Landé's papers. He explains theoretically the line intensities in the partial Paschen-Back effect.

Pauli is enthusiastic about Landé's recent paper and the assumption that the optical doublets and X-ray doublets are in principal the same phenomenon.

Pauli summarizes his work on spectral intensities using the correspondence principle. He compares it with Ornstein's results. He makes remarks on satelite-lines paper (in: Naturwissenschaften : 12 (1924), pp.741).

Heisenberg writes more about the intensities of spectral lines.

Pauli says his difficulties with model pictures. He reports on his "generalization" of Stoner's work for closing of shells. He comments the new edition of Sommerfeld's Atombau.